The Department of Toxic Substances Control also has drastically reduced fines against polluting firms and reduced the number of cases it sends to prosecutors, the Los Angeles Times said, citing interviews and records from courts, the department and other agencies.

The department is responsible for regulating more than 100,000 businesses that generate hazardous waste in the state.

However, the Times review concluded that:

— A quarter of California's 118 major hazardous waste facilities are operating on expired permits.

— Hundreds of companies have walked away from contaminated sites, leaving the cleanup costs to taxpayers. The department has acknowledged that it did not even try to collect $140 million in such costs from 1987 through last year, although it has now recovered about $16 million under a new billing procedure.

— The department has drastically reduced its use of fines in recent years. Companies agreed to pay a total of $2.45 million a year on average from 2008 to 2012 — half the average of the previous five years.

— The department has sharply reduced the number of cases it submits to prosecutors for possible criminal charges — an average of four per year in the past five years compared to more than 40 a year in the previous five years.

Problems have been blamed on staff cuts, inconsistent standards for regulations and enforcement, high turnover at the top; it's had seven directors in 10 years.

Department Director Debbie Raphael declined to be interviewed for the Times story, but she has previously said the agency is working to correct inherited issues.

"We are committed to owning up to the problems and taking the steps necessary to ensuring they are fixed once and for all," she said in a statement posted on the agency's website.

Two cases illustrate the department's sluggish response:

In 1992, nitric acid leaked from a tank at Electro-Forming Co., a metal plating company in the San Francisco Bay Area city of Richmond, and created a toxic cloud that reached nearby homes.

"People were coughing. They were gasping for air," recalled Denny Larson, who went to the scene. More than 125 people were taken to hospitals.

More than 20 years later, a study that the department ordered to determine the extent of contamination from the site still has not been completed.

In Southern California, public outcry recently arose over Exide Technologies, a battery recycler in the southern Los Angeles suburb of Vernon.

The plant has been smelting the lead in batteries for decades with a temporary permit that was only intended to give it time to meet legal standards for disposing of toxic materials, the Times said.

In March, the South Coast Air Quality Management District reported that arsenic emissions created an elevated risk of cancer for as many as 110,000 people.

The state finally tried to suspend the plant's operations, but a judge this summer allowed operations to resume.

Earlier this year, Exide agreed to set aside $7.7 million to pay for new filters to lower its emissions. In return, the state dropped efforts to shutter the plant, although the air quality district still is seeking to close the plant until its air pollution control systems are improved.

"The department has unfortunately had a long history of constant turnover and uncertain standards — a situation that has left permittees frustrated with frequently shifting oversight, guidance, requirements and deadlines," said Bud Desart, a senior director of Exide's recycling group.

However, Exide officials are now working to obtain a permanent permit, he said.

Raphael has called the department's record on Exide "an embarrassment."

"There is a systemic problem with enforcement of regulations to protect the public," said state Sen. Kevin de Leon, D-Los Angeles, whose district includes Vernon. "It's the agency's main responsibility to ensure that these facilities pose no harm, and the reality is, that is not happening."

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